Performance of Fh - Mfsk Cellular Mobile Radio in the Presence of Nonsynchronous Users

(Oil) and (lll)B. This observation is consistent with the work of Coldren et a/. on the sensitivity of the etch rate of InP in HC1 to the crystal orientation. The profile in Fig. 2 was obtained using a mixture of 1(HC1): 3(H3POJ (again the grating orientation is (Oil)), In this case the profile is rectangular with a depth of c*2000 A. Here, the etched depth is not limited by the formation of intersecting slow-etching planes, and the rectangular profile produced is particularly attractive for use in second-order DFB lasers since a straightforward Fourier analysis shows it to contain =s: 1270 A of the desired 0-23 jum period harmonic component (the mark/space ratio was taken to be =* 1/3). By comparison the commonly used triangular profile contains only 666 A of this component.